A conference on the Pulmonary Circulation and Gas Exchange will be held in Colorado from 9/19/91 to 9/22/91. This is the fifth in the series of Grover Conferences on the Pulmonary Circulation. The purpose of the meeting is to review the current status of research on the physiology and pathophysiology of the pulmonary vasculature and gas exchange and to suggest approaches to the important questions that remain to be answered. Such a review will define the data base that is now accepted and thus prevent duplication of prior work, a common problem which is appropriately criticized. Two groups will participate. Twenty senior scientists of international reputation for their work in the pulmonary circulation will analyze progress in their respective areas of work. All the speakers listed in the program have agreed to attend. The second group will consist of 40 active investigators from laboratories throughout North America. They will chair the sessions, participate in the discussions and workshops, and help to formulate the recommendations arising from the conference. It is important to hold this meeting now for two reasons. Pulmonary vascular research, like other areas of biomedical science, is searching for ways to integrate the data coming from cellular and molecular studies with its base of physiologic knowledge. The two groups of participants are well suited to accomplish this. Secondly, it will be apparent that the eminent speakers, who have led this field for the last 20 years, will not be available indefinitely. After this intense period of research on the pulmonary circulation and gas exchange, we must capture their unique perspectives on the problems that remain. The format of the meeting will be similar to that of the previous Grover Conferences. It will be held at an isolated conference center to promote both formal and informal discussion. In addition to the talks and subsequent discussion, time is allotted for workshops which will involve both the speakers and the other scientists attending. The chairperson of a particular session will also chair the workshop on that subject, will be responsible for writing the recommendations of the group, and will present those recommendations at the final session of the conference. The logistics of organizing the meeting pose no problem, as this is the fifth in the series of Grover Conferences. The information developed at the meeting will be disseminated through the participation of the 40 active investigators and through a book, which Futura Publishing Company, Inc., New York, has agreed to publish. Each speaker has agreed to write a chapter for the book. The recommendations of the working groups may also be included, if NIH does not choose to publish them separately elsewhere. The budget request covers only the lodging and transport of the speakers and chairpersons with a small cost for organization.